Comparison of magnetic resonance imaging and ultrasonography in the evaluation of abdominal aortic aneurysms.

Magnetic resonance imaging (MRI) was used to evaluate abdominal aortic aneurysms in 27 patients. The findings were compared retrospectively with CT, ultrasound (US), and angiography in 17 cases and prospectively with US in 10 cases. MRI identified the renal arteries in all cases, demonstrated involvement at or above the origin of the renal arteries in eight patients, and showed extension of the aneurysm into the iliac arteries in 12 cases. The outer dimension of the aneurysm, the diameter of the residual lumen, and the length of the aneurysm were measured easily from the MR images. The measurements of transverse dimension of the abdominal aortic aneurysm were similar for MRI, CT, and US. MRI more accurately defined extension above the renal arteries and below the aortic bifurcation. It is concluded that MRI provides the necessary information for the surveillance and preoperative evaluation of abdominal aortic aneurysms.